In the present description and in the ensuing claims, the term “tool head” is understood to indicate a tool head designed for performing any industrial operation, such as for example a clinching operation or a welding operation, for example electrical spot welding or laser welding, or even only an operation of movement of a piece with the aid of a gripping tool. The term “tool” is understood to indicate any tool or apparatus used on the tool head, such as for example a clinching roller or a pair of electrodes for electrical welding, or an optical device for focusing a laser beam, or a gripping tool.
The invention is in general applicable to any system that envisages the use of a tool head for performing industrial operations. According to a preferred application, the invention regards systems in which the tool head is carried by a robot, in particular a multi-axis industrial robot of the type including a base structure, an articulated robot wrist, to which the tool head is removably connected, and a chain of mutually articulated robot elements that connect the base structure of the robot to the robot wrist. In a specific example, the tool head carried by the robot is a clinching head, provided with one or more clinching rollers pre-arranged for engaging and rolling along the extension of an edge of a metal sheet to be bent (for example, along the perimeter of a motor-vehicle door structure on a line for the production of motor-vehicle doors). In the case of this specific application, associated to the clinching head are one or more force sensors that detect the load on the clinching rollers during execution of the clinching operation.
As has been mentioned, the present invention is in any case of general application and can be envisaged also in the case of a tool head manoeuvred manually by an operator, such as for example a manually controlled electrical-spot-welding head.
Whatever the type of tool head used and whatever the configuration of the system, there exists the problem of acquiring the data coming from the sensors associated to the tool head with means that are as far as possible simple and of contained dimensions.
It has already been proposed to associate to a tool head carried by a robot a wireless transmission unit that will enable control and monitoring of operation of the tool head in wireless mode (see, for example, the documents Nos. DE 20 2011 000 315 U1 and U.S. 2006-0122730 A1). However, the known systems have not solved the further problem connected to the need to guarantee a high operating autonomy of the system, and to the simultaneous need to avoid use of power-supply cables, which, above all in the case of a tool head carried by a robot, would entail constructional complications and would render operations for replacement of the tool head more laborious.
It would instead be desirable to reduce or eliminate altogether the electrical wiring that connects the tool head to the robot. This wiring is in fact subject to a considerable wear on account of the repeated cycles of deformation to which it is subjected during the service life of the robot and must consequently be replaced periodically, which determines losses of productivity due to the times for stoppages required for replacement operations.